Myo-Inositol hexakisphosphate is an intermediate in inositol phosphate metabolism. It can be generated from D-myo-Inositol 1,3,4,5,6-pentakisphosphate via the enzyme inositol-pentakisphosphate 2-kinase (EC:2.7.1.158). Myo-Inositol hexakisphosphate is also known as phytic acid. It can be used clinically as a complexing agent for removal of traces of heavy metal ions. It acts also as a hypocalcemic agent. Phytic acid is a strong chelator of important minerals such as calcium, magnesium, iron and zinc and can therefore contribute to mineral deficiencies in developing countries. For people with a particularly low intake of essential minerals, especially young children and those in developing countries, this effect can be undesirable. However, dietary mineral chelators help prevent over-mineralization of joints, blood vessels, and other parts of the body, which is most common in older persons. The Journal of Environmental Nutrition (April 2004 volume 27 issue 4) has also stated phytic acid may be considered a phytonutrient, providing an antioxidant effect.

Acts as a phosphoinositide 5- and phosphoinositide 6-phosphatase and regulates cellular levels of inositol pentakisphosphate (InsP5) and inositol hexakisphosphate (InsP6). Also acts as a 2,3-bisphosphoglycerate 3-phosphatase, by mediating the dephosphorylation of 2,3-bisphosphoglycerate (2,3-BPG) to produce phospho-D-glycerate without formation of 3-phosphoglycerate. May play a role in bone development (endochondral ossification).

Cleaves a beta-phosphate from the diphosphate groups in PP-InsP5 (diphosphoinositol pentakisphosphate), suggesting that it may play a role in signal transduction. Also able to catalyze the hydrolysis of dinucleoside oligophosphates, with Ap6A and Ap5A being the preferred substrates. The major reaction products are ADP and p4a from Ap6A and ADP and ATP from Ap5A. Also able to hydrolyze 5-phosphoribose 1-diphosphate.

Cleaves a beta-phosphate from the diphosphate groups in PP-InsP5 (diphosphoinositol pentakisphosphate) and [PP]2-InsP4 (bisdiphosphoinositol tetrakisphosphate), suggesting that it may play a role in signal transduction. InsP6 (inositol hexakisphophate) is not a substrate. Acts as a negative regulator of the ERK1/2 pathway. Also able to catalyze the hydrolysis of dinucleoside oligophosphates, with Ap6A and Ap5A being the preferred substrates. The major reaction products are ADP and p4a from Ap6A and ADP and ATP from Ap5A. Also able to hydrolyze 5-phosphoribose 1-diphosphate.

Cleaves a beta-phosphate from the diphosphate groups in PP-InsP5 (diphosphoinositol pentakisphosphate), PP-InsP4 and [PP]2-InsP4 (bisdiphosphoinositol tetrakisphosphate), suggesting that it may play a role in signal transduction. Also able to catalyze the hydrolysis of dinucleoside oligophosphate Ap6A, but not Ap5A. The major reaction products are ADP and p4a from Ap6A. Also able to hydrolyze 5-phosphoribose 1-diphosphate.

Phosphorylates Ins(1,3,4,5,6)P5 at position 2 to form Ins(1,2,3,4,5,6)P6 (InsP6 or phytate). InsP6 is involved in many processes such as mRNA export, non-homologous end-joining, endocytosis, ion channel regulation. It also protects cells from TNF-alpha-induced apoptosis.